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<p>Reports a problem when a mutable value as a list or dictionary is detected in a default value for
  an argument. <br/>
  Default argument values are evaluated only once at function definition time,
  which means that modifying the
  default value of the argument will affect all subsequent calls of that function.</p>
<p><b>Example:</b></p>
<pre><code>
def func(s, cache={}):
    cache[s] = None
</code></pre>
<p>When the quick-fix is applied, the code changes to:</p>
<pre><code>
def func(s, cache=None):
    if cache is None:
        cache = {}
    cache[s] = None
</code></pre>
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